Melanoma skin cancer can be fatal unless caught early, but most skin lesions are harmless. Dermoscopy with training can help with diagnosis. This blog is not a substitute for a medical opinion-if you are worried about a changing or funny looking mole or spot, get it checked by a doctor with suitable skills.

Odd looking mole on shoulder

BY THE WAY a little reminder for 2018. This blog is a free educational resource aimed at doctors and nurses world wide who are using dermoscopy to diagnose skin lesions. Obviously the general public can see it, and I take that into account as I write. However, it is aimed at medical professionals. All patients have given their consent for their images to be used in education and I am careful to avoid posting identifying features. If anyone has a mole that is changing, or looks weird in any way, you should see a suitably qualified doctor for diagnosis. I don’t offer a tele-consultation service, and if I did I’d have to get suitable indemnity cover and charge people for opinions. I have no intention of doing that-this blog is PURELY FOR EDUCATION.

Please bear this in mind. Happy New Year!

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A middle aged white person presented with this 8mm diameter changing mole on the shoulder.

At a glance, we don’t like it. It violates the ugly duckling rule and the ABCD rule. Dermoscopy is hardly necessary, although at this distance it could still just about be an atypical or traumatised benign lesion.

Any doubts are now removed, and the only decision to make is how quickly can we get this where it belongs, into a jar of formalin on the way to the histopathologist.

let us consider several diagnostic algorithms.

(A) chaos and clues. Is it chaotic? Yes. There are multiple colours and structures arranged in a disorderly way. Is it a seborrhoeic keratosis? I see no evidence for this. Therefore under the ‘chaos and clues’ algorithm, this will be excised.

Are there any clues? I can see some fragments of disrupted network around 11 and 4 o’clock, pointing to a melanocytic lesion. There are also brown dots and globules which point to a melanocytic lesion. This leads us neatly into …

(B) the two step algorithm.

step 1-is it melanocytic? Yes, because of the network and globules mentioned above.

step 2-could it be a melanoma? Yes, because the network, globules and other features are arranged very disorderly.

The two step algorithm is of limited use, but like a tin opener, sometimes it is the perfect tool and you don’t need any other.

I’m not going to copy the 7 points out, click on the link for a better experience, but they include irregular network, irregular dots and globules, irregular streaks, and irregular pigmentation-all of which we see here. As I as saying to a patient in clinic today, if I was limited to just one word to describe melanoma, the word would be irregular.

So the score is 4 out of 7 of the seven point check list. The original form of this algorithm is a points system, but professor Argenziano, who originated the system, now says that is any one of the seven features are present in a strong, positive form, that is enough to justify excision.

PS the other 3 points are atypical vessels, blue-white veil, and regression structures.

SO, we used 3 different algorithms, and they all gave the same answer. Harald Kittler, whose work I admire, says that he experienced dermoscopist learns and uses all algorithms and then adapts his or her own algorithm. As i see it, algorithms are like tools, or fishing flies, in a box. If carefully chosen, they are all good, but in different situations one will be better than the others. The art is knowing when. Experience comes with viewing and thinking about many cases, which is why I post cases here.

This proved to be a melanoma of medium thickness. Shame it wasn’t removed earlier.